Sabre saws with lockable swivel saw bars

ABSTRACT

A sabre saw is provided with means for driving the saw bar in a linear reciprocatory motion from a rotary electric motor, while at the same time, permitting the saw bar to be manually rotated or selectively locked in position about its own axis to set the cutting edge of the saw blade in different angularly oblique positions relative to the line of movement of the tool. A control knob is journaled to rotate within the housing, at the top of the front end thereof. The control knob is coupled to the saw bar by means of an internally slotted saw bar bushing in the control bar which reciprocally receives a pin fixed in the saw bar. Though the saw bar is free to reciprocate within the control knob, turning of the control knob will cause a like turning of the saw bar, so that the control knob determines the angular position of the saw bar. A lock pin is transversely slidable with respect to the control knob, and is actuated by a slide button mounted in the handle of the housing. The lock pin has a tapered tip which will lock or unlock the control knob by engagement with angled slots found in the external flange of the saw bar bushing upon aligning said slot with the lock pin by turning the control knob. The slots are set at convenient angles of cutting. When the lock pin is removed from the slots in the flange, the control bar is in an unlocked position and can be manually manipulated so as to suitably position the cutting edge of the saw blade, as in scroll cutting.

llnited States atet [191 Batson SABRE SAWS WITH LOCKABLE SWIVEL SAW BARS [75] inventor: William A. Batson, Pickens, SC.

[73] Assignee: The Singer Company, New York,

22 Filed: Mar. 9, 1972 21 Appl.No.: 233,208

[56] I References Cited UNITED STATES PATENTS 3,494,390 2/1970 Dudek ..30/394 Primary ExaminerDonald R. Schran Att0rneyMarshall J. Breen et al.

[57] ABSTRACT A sabre saw is provided with means for driving the saw bar in a linear reciprocatory motion from a rotary [4 1 May 1,1973

electric motor, while at the same time, permitting the saw bar to be manually rotated or selectively locked in position about its own axis to set the cutting edge of the saw blade in different angularly oblique positions relative to the line of movement of the tool. A control knob is joumaled to rotate within the housing, at the top of the front end thereof. The control knob is coupled to the saw bar by means of an internally slotted saw bar bushing in the control bar which reciprocally receives a pin fixed in the saw bar. Though the saw bar is free to reciprocate within the control knob, turning of the control knob will cause a like turning of the saw bar, so that the control knob determines the angular position of the saw bar. A lock pin is transversely slidable with respect to the control knob, and is actuated by a slide button mounted in the handle of the housing. The lock pin has a tapered tip which will lock or unlock the control knob by engagement with angled slots found in the external flange of the saw bar bushing upon aligning said slot with the lock pin by turning the control knob. The slots are set at convenient angles of cutting. When the lock pin is removed from the slots in the flange, the control bar is in an unlocked position and can be manually manipulated so as to suitably position the cutting edge of the saw blade, as in scroll cutting.

7 Claims, 6 Drawing Figures SABRE SAWS WITH LOCKABLE SWIVEL SAW BARS BACKGROUND OF THE INVENTION required the operators two hands at the control knob and in some instances, the locking aperture may have been worn or oversized, resulting in a loose fit and excessive wobble of the saw bar during cutting in the locked position.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an improved locking and unlocking means for sabre saws having swivel saw bars; which is simple, economical and reliable; which overcomes the prior art disadvantages; which has the actuator button mounted in the handle for ease of operation; which uses a lock pin connected to the actuator button; which uses a slide lock pin; which uses a tapered slot and a tapered pin to mate in locked position; and which uses a plurality of tapered slots set at predetermined angles to mate with a tapered pin in locked position.

Other objects and advantages will be apparent from the following description of one embodiment of the invention and the novel features will be particularly pointed out hereinafter in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS This invention is illustrated in the accompanying drawings in which:

FIG. 1 is a longitudinal elevational view, partly in section, of a sabre saw illustrating a preferred embodiment of the present invention.

FIG. 2 is a top plan view, partly in section, showing a portion of the handle and gear housing, with the control knob shown in phantom to expose slotted bushing flange having the lock pin inserted therein in locked position.

FIG. 3 is a top plan view, partly in section, similar to FIG. 2, except the slotted bushing flange is not engaged by the lock pin and is therefore free, along with the control knob (shown in phantom), to rotate the saw bar.

FIG. 4 is a fragmentary, enlarged top plan view of the tapered tip of the lock pin which is just entering the tapered slot of the bushing flange during the initial stage oflocking the control knob.

FIG. 5 is a fragmentary, greatly enlarged top plan view of the tapered tip of the lock pin securely locked within the tapered slot of the bushing flange.

FIG. 6 is a top plan view illustrating the use of the sabre saw of the present invention in cutting a circular disc from a work piece.

DESCRIPTION OF THE INVENTION Referring now to FIG. 1 of the illustrated embodiment of the invention, a shaft 10 of a driving electric motor 12 mounted in the housing 14 extends into the gear housing 16 and is formed with a splined portion 18 which meshes with and drives a gear 20 journaled in the gear housing 16. The gear 20 carries an eccentric pin 22 surmounted by a roller 24 which engages the slide portion of a crosshead 26. The crosshead 26 has a central transverse opening 28 in communication with the slide portion. A pair of aligned holes 30 are formed in the top and bottom of the crosshead 26 perpendicular to the transverse opening 28 of a circular diameter just slightly larger than the cross-sectional diameter of a saw bar 32 which extends therethrough.

The saw bar 32 is free to turn about its axis within the holes 30 of the crosshead 26, but is held axially captive by an annular collar 34 disposed in the opening 28 and affixed to the saw bar 32 by a split pin 36 as illustrated in FIG. 1. The saw bar 32 is joumaled for linear movement in a sleeve bearing 38 secured in the bottom portion of a gear housing cover 40, and a journal bushing 42 secured in the top 41 of the combined gear housing 16 and the gear housing cover 40, for purposes more fully explained hereinafter.

A gear 44 journaled in the gear housing 16 meshes with gear 20, and by means of an eccentric pin 46 and roller 48, drives an upper balancing crosshead 50 which is free to turn and slide on the saw bar 32.

Upon operation of the sabre saw, the motor shaft 10 will drive the gear 20 which, through pin 22 and roller 24 working in crosshead 26, transmits linear axial reciprocatory motion to the saw bar 32 and drives an affixed saw blade 52 having a cutting edge 54 in a linear reciprocatory path substantially normal to the plane of a work-contacting shoe 56.

In the conventional sabre saw, there is no structure for selectively determining the angular position of the saw bar about its own axis, and thus, no means, other than for straight cutting, for presenting the cutting edge of the saw blade in a predetermined angular position with respect to the work.

In the illustrated embodiment of the invention, an improved means in the form of a control knob assembly generally designated as 60, is provided for selectively and manually controlling the angular position of the saw bar 32 while it is reciprocating to provide the cutting strokes for the saw blade 52. The control knob assembly 60 includes the journal bushing 42 toiwhich is affixed a control knob 62 by means of a set screw 64.

The journal bushing 42 has internal diametrically positioned slots 66 communicating with the central aperture 68 in which an end portion 70 of the saw bar 32 reciprocates. A pin 72 is secured to the end portion 70 in slidably guiding engagement with the slots 66. The pin 72 is preferably secured to the saw bar 32 in such a position that its axis lies in the plane of the saw blade 52.

The control knob 62 has a lower section 74 and an upper section 76. The lower and upper sections form a hollow chamber 78 and are cemented to each other about their annular common periphery, each of which terminate in the same plane. The control knob 62, as illustrated in FIG. 1, extends forwardly slightly more than rearwardly, with the front side 80 slightly wider than the rear side 82 as shown in FIG. 2. The upper section 76 of the front side 80 is indexed at 84 to form a pointer line lying in substantially the same plane as the sawblade 52. The lower section is molded with a metal insert 86 having an internal diameter similar to the external diameter of the upper end 88 of the bushing 42 which projects above the top 41 to permit a sliding fit therebetween. The rearside of the insert 86 has a taped hole 90 to which the set screw 64 is threaded. The top of the upper end 88 has diametrically positioned recesses 92 formed with their axis perpendicular to plane in which the slots 66 are disposed so that each would intersect the longitudinal axis of the bushing 42, which in turn, is coincident to the axis of the saw bar 32. The recesses 92 serve to position the control knob 62 which has diametrically formed projections 94 which seat within the recesses 92, and thus align the index pointer 84 with the blade 52.

The journal bushing 42 is trapped in axial position, but free to rotate within the aperture 96 formed in the top 41. A flange 98 is formed below the upper end 88 to extend radially outwardly from the longitudinal axis of the bushing 42. The flange 98 is illustrated in FIGS. 1, 2 and 3, and has four tapered slots 100 extending radially inwardly from the circumference thereof. The slots 100 are widest at the circumference and decrease in width toward their base. The flange 98 is seated within a recess 102 formed in the top 41. The depth of the recess 102 is such that the lower portion of the 62 extends therein as shown in FIG. 1. The lower end 104 of the bushing 42, below the flange 98, extends beneath the underside of the top 40a, wherein it is fitted with a wavy washer 106, a flat washer 108, and a split retainer clip 110 disposed in an annular groove 112 therein. Thus, the bushing 42 is prevented from moving axially downwardly by the integral flange 98, and is prevented from being lifted upwardly by the spring clip 110, while the wavy washer 106 normally biases the bushing 42 in the axially downwardly direction.

A handle 114 is secured to the gear housing 16 in superposition to and cantilevering over the motor in the housing 14 and carries a conventional trigger switch 116 and associated lock button 118 on the underside thereof for actuating the motor 12 in the usual manner. A slide button or switch 120 is slidably mounted within the handle 114 adjacent the upper surface thereof, whereby the button portion 122 having a stepped upper surface which inclines downwardly in either direction from the high point in the center thereof, projects through an aperture 124 formed in the upper surface of the handle 114 for ease and convenience of operator actuation thereof. The handle 114 is so shaped to aid the operator in using a single hand to control the trigger switch 116 and the slide button 120 with one hand, as for example, by using the index finger to depress or release the trigger switch 116, while using the thumb to actuate either the lock button 118 associated with the trigger switch 116 or independently and preferably when the motor 12 is deactivated, to use the thumb to actuate the slide button 120.

The slide button 120 is part of the lock pin assembly, designated generally 126, which also includes a leaf spring keeper 128 and a lock pin 130. The slide button 120 has horizontally extending flanges 132 on either side thereof to be slidably received in horizontal grooves (not shown), formed in the mated sections 134 of the handle 114. The bottom surface of the slide button 120 has a downwardly extending projection 136 with tapered sides which extend toward each other to terminate in a flat base portion 137 thereof. The keeper 128 has a vertical section which is secured against a vertical wall ofthe gear housing 16 by a screw 138. The

keeper 128 cantilevers out from the vertical wall to terminate in a two-sided raised tapered finger 140, which is positioned to engage one or the other of the tapered sides of the projection 136. The keeper 128 acts to prevent accidental movement of the slide button 120, but is a relatively light leaf spring which, with the aid of the tapered sides, may be easily displaced so as to permit ready movement of the slide button 120. Other forms of keepers could be substituted for keeper 128; for example, a spring loaded detent and ball.

A horizontal circular opening 142 is formed in the top 41 with its longitudinal axis parallel to the longitudinal disposition of the handle 1 14. The lock pin 130 is disposed in the opening 142, which communicates with the base of the recess 102 and is formed in alignment with the horizontal disposition of the flange 98, as illustrated in FIG. 1. The tip 143 of the lock pin 130 is tapered as at 144 shown best in FIGS. 4 and 5, and in the preferred form the angle of the taper 144, is slightly smaller than the angle of the taper of the sides of the slots 100. Of course, if desired, the respective tapers could correspond and be equal to each other.

The lock pin assembly 126 is shown in the locked straight cut position, as shown in FIGS. 1 and 2. In the straight out position, the index pointer 84 of the control knob 62 is in alignment with the lock pin 130 and the slide button 120, is in the forward position with the tip 143 of the lock pin 130 engaged within the slot 100. In FIGS. 1 and 2, the forward position of the slide button 120 is in the leftward direction to place the projection 136 on the left side of the bent finger 140. In this position, the control knob 62 is locked against rotary move ment about the axis of the saw bar 32.

The slots are cut at 90 intervals, so that the control knob 62 may be locked in position at 0 which is equal to straight cutting, or at convenient angles corresponding to 90, 180, or 270. It is understood that slots could be formed corresponding to any desired angle, so as to lock the control knob assembly 60 at such angle. The saw bar 32 is always free to reciprocate and turning of the control knob 62 will result in like turning of the saw bar 32 about its axis because of the connection between the pin 72 within the slots 66 of the bushing 42.

When scroll cutting is desired, the slide button of the lock pin assembly 126 will be placed in a position oat the rightward end of the aperture 124, as illustrated in FIG. 3, in which the projection 136 will engage the right side of the bent finger 140,and thereby remove the lock pin from contact within any of the slots 100 of the flange 98. This frees the control knob 62 to rotate the journal bushing 42 and companion saw bar 32 therewith. One example of scroll cutting is depicted in FIG. 6, wherein a sabre saw embodying the present invention is used to cut a circular disc from a workpiece. If a conventional sabre saw, i.e., one not having the swivelling saw bar feature of the present invention, is used to follow a curve pattern of this kind, it is necessary to orientate the entire tool to follow the curve. Thisinvolves the controlled guiding and turning of considerable mass from a position offset from the cutting axis of the tool which becomes increasingly difficult as the radius of curvature becomes small relative to the tool dimensions. However, by use of the control knob assembly 60 of the illustrated embodiment of the present invention, it is possible to guide the saw bar 32 from a position directly above the cutting axis of the tool by rotating the control knob 62 which requires only the turning of the small mass of the saw bar itself, thus enabling the accurate cutting of intricate patterns more readily. With the full 360 swiveling of the saw bar independent of the rest of the tool body, it is only necessary to rotate the control knob 62 to guide the cutting edge 54 as desired, and let the body of the tool assume any angle that it may take.

To change from scroll cutting to straight cutting, or from one predetermined angle of straight out to another predetermined angle of straight cutting, it is necessary to engage the lock pin assembly 126 within the control knob assembly 60 by insertion of the lock pin 130 within one of the slots 100. The operator may do this by holding one hand upon the handle 114 with the thumb upon the slide button 120, and would place his free hand upon the control knob 62 to turn and align the control knob 62 and its captive saw bar 32 and saw blade 52 in the desired position. Since each of the slots 100 fall along the 90 quadrant lines and using the saw bar 32 and the index pointer 84 as a reference marker, the operator could, with a little practice or a little movement, position the control knob 62 so as to align one of the slots 100 adjacent the hole 142. Once the slot 100 is aligned with the lock pin 130, the operator would slide the slide button 120 forwardly, or as viewed in FIG. 1 leftwardly, to insert the tapered tip 43 within the aligned slot 100. Both the slot 100 and the tip 143 have been tapered for ease of insertion and positive connection therebetween. FIG. 4 illustrates the tip 143 of the lock pin 130 being placed within the tapered slot 100 at a point in time when the slide button 120 and lock pin 130 are just being moved forwardly into the previously aligned slot 100. If the slot 100 is misaligned, the control knob 62 will be turned in either direction simultaneously with operation of the slide button to insert the lock pin 130 within the adjacent slot 100. The lock pin 130 is shown in locked position in FIG. 5, wherein the tapered tip 143 engages the outermost end of the sides of the slot 100 to positively lock the control knob 62 and connected saw bar 32 and saw blade 52 in adjusted position. Engagement between the tapered slot 100 and the tapered tip 143 of the lock pin 130 provides the dual advantage of ease of insertion and a tight wobble-free connection in locked position whereby the knob 62 is positively held to correspondingly hold the saw blade 52 along the desired line and eliminate any deflection therefrom due to a loose fitting lock part. This has been a problem in prior art devices, in that wear or manufacturing tolerances of the connecting lock parts would lead to wobble of the connected parts and a deviation of the saw blade 52 from the line of the straight cutting position. Due to the uneven taper of the slot 100 and the taper 144 of the lock pin 130, any wear or difference in manufacturing tolerance of the parts is automatically compensated for, and so long as the slide button 120 remains in the locked or leftward position as shown in FIG. 1, the lock pin 130 will firmly engage the slot 100 of the flange 98 ofthe bushing 42 and prevent any turning movement of the control knob assembly 60, saw bar 32 and saw blade 52.

To change from one position of straight cutting to another requires unlocking of the lock pin assembly 126 and turning of the control knob assembly to a new position, and subsequently locking the lock pin 130 within the aligned slot 100. To change from straight cutting to scroll cutting merely requires unlocking of the lock pin assembly 126 by sliding the slide button rightwardly to remove the lock pin from engagement with any of the slots 100 of the flange 98, as illustrated in FIG. 3.

It will be understood that various changes in the details, materials, arrangements of parts and operating conditions, which have been herein described and illustrated in order to explain the nature of the invention, may be made by those skilled in the art within the principles and scope of the invention.

Having thus set forth the nature of the invention, what I claim herein is:

1. In a power operated portable saw having a housing and a saw bar including driving means for reciprocating the saw bar along a linear axis while permitting the saw bar to freely be rotated about said axis, means controlling the rotation of said saw bar comprising:

a. a journal bushing rotatively connected to the housing and projecting outwardly thereof,

b. the journal bushing formed with a longitudinal slot parallel to the axis,

0. a pin fixed to the saw bar transversely of the axis and slidably engaged with the slot,

a control knob affixed to the journal bushing at the outward projection thereof,

e. a flange formed on the bushing to extend perpendicular to the axis,

f. a slot formed on the flange,

g. a handle connected to the housing,

h. a trigger switch mounted in the handle and externally accessible to control the operation of the driving means of said saw,

i. a lock pin retractably mounted in the housing and disposed in the plane in which the flange lies and to be shifted in a path transverse to the axis,

j. a lock switch shiftably mounted in the handle and externally accessible, and in spaced relation to the trigger switch, each switch actuatable by the same hand of the operator,

k. the lock pin connected to the lock switch, and

. the lock switch movable between a lock position and an unlock position wherein in the unlock position the control knob is free to rotate the saw bar, and in the lock position the lock pin will be inserted into the slot upon alignment therebetween.

2. The combination claimed in claim 1 wherein:

a. the lock switch slidably actuated to slide the lock pin into and out of engagement with the slot upon the slot being turned into alignment therewith.

. The combination claimed in claim 2 wherein:

a. the flange of thejournal bushing annularly shaped,

b. a plurality of slots formed circumferentially about the flange at predetermined angles, and

c. the control knob to rotate the flange to bring any one of the slots into alignment with the lock pin.

4. In a power operated portable saw having a housing and a saw bar including driving means for reciprocating the saw bar along a linear axis while permitting the saw bar to freely be rotated about said axis, means controlling the rotation of said saw bar comprising:

a. a journal bushing rotatively connected to the housing and projecting outwardly thereof,

b. the journal bushing formed with a longitudinal slot parallel to the axis,

0. a pin fixed to the saw bar transversely of the axis and slidably engaged with the slot,

d. a control knob affixed to the journal bushing at the outward projection thereof,

e. a flange formed on the bushing to extend perpendicular to the axis,

f. a slot formed on the circumference of the flange to nally accessible for sliding the pin into and out of engagement with the slot, and

i. the retractable pin having a tapered tip, the surface of which will contact the opposite sides of the slot to positively position the same and prevent wobble of the control knob whenever the pin is engaged within the slot.

5. The combination claimed in claim 4 wherein:

a. a plurality of said slots formed in the flange at predetermined angles with respect to the axis.

6. The combination claimed in claim 4 wherein:

a. the angle of taper at the tip of the pin at least as large as the angle of the taper of the opposite sides of the slot.

7 The combination claimed in claim 6 wherein:

a. the angle of the taper at the tip of the pin larger than the angle of the taper of the opposite sides of the slot, whereby said tip will contact the sides adjacent the outer end thereof. 

1. In a power operated portable saw having a housing and a saw bar including driving means for reciprocating the saw bar along a linear axis while permitting the saw bar to freely be rotated about said axis, means controlling the rotation of said saw bar comprising: a. a journal bushing rotatively connected to the housing and projecting outwardly thereof, b. the journal bushing formed with a longitudinal slot parallel to the axis, c. a pin fixed to the saw bar transversely of the axis and slidablY engaged with the slot, d. a control knob affixed to the journal bushing at the outward projection thereof, e. a flange formed on the bushing to extend perpendicular to the axis, f. a slot formed on the flange, g. a handle connected to the housing, h. a trigger switch mounted in the handle and externally accessible to control the operation of the driving means of said saw, i. a lock pin retractably mounted in the housing and disposed in the plane in which the flange lies and to be shifted in a path transverse to the axis, j. a lock switch shiftably mounted in the handle and externally accessible, and in spaced relation to the trigger switch, each switch actuatable by the same hand of the operator, k. the lock pin connected to the lock switch, and l. the lock switch movable between a lock position and an unlock position wherein in the unlock position the control knob is free to rotate the saw bar, and in the lock position the lock pin will be inserted into the slot upon alignment therebetween.
 2. The combination claimed in claim 1 wherein: a. the lock switch slidably actuated to slide the lock pin into and out of engagement with the slot upon the slot being turned into alignment therewith.
 3. The combination claimed in claim 2 wherein: a. the flange of the journal bushing annularly shaped, b. a plurality of slots formed circumferentially about the flange at predetermined angles, and c. the control knob to rotate the flange to bring any one of the slots into alignment with the lock pin.
 4. In a power operated portable saw having a housing and a saw bar including driving means for reciprocating the saw bar along a linear axis while permitting the saw bar to freely be rotated about said axis, means controlling the rotation of said saw bar comprising: a. a journal bushing rotatively connected to the housing and projecting outwardly thereof, b. the journal bushing formed with a longitudinal slot parallel to the axis, c. a pin fixed to the saw bar transversely of the axis and slidably engaged with the slot, d. a control knob affixed to the journal bushing at the outward projection thereof, e. a flange formed on the bushing to extend perpendicular to the axis, f. a slot formed on the circumference of the flange to extend inwardly therefrom in decreasing cross-sectional area so that the base of the slot is a smaller dimension than the circumferential end thereof to produce tapered sides which move toward one another in the direction of the axis, g. a retractable pin slidable in the housing in a path transverse to the axis to be engaged in the slot upon the slot being aligned therewith, h. a slide button mounted in the housing to be externally accessible for sliding the pin into and out of engagement with the slot, and i. the retractable pin having a tapered tip, the surface of which will contact the opposite sides of the slot to positively position the same and prevent wobble of the control knob whenever the pin is engaged within the slot.
 5. The combination claimed in claim 4 wherein: a. a plurality of said slots formed in the flange at predetermined angles with respect to the axis.
 6. The combination claimed in claim 4 wherein: a. the angle of taper at the tip of the pin at least as large as the angle of the taper of the opposite sides of the slot.
 7. The combination claimed in claim 6 wherein: a. the angle of the taper at the tip of the pin larger than the angle of the taper of the opposite sides of the slot, whereby said tip will contact the sides adjacent the outer end thereof. 